U.S. Pat. No. 6,013,741 issued Jan. 11, 2000 to Ohtani et al., assigned to Mitsui teaches the design of a reactor to permit the rapid introduction of a kill gas into a fluidized bed reactor to rapidly stop a reaction in the event of an equipment failure.
U.S. Pat. No. 8,435,920 issued May 7, 2013 to White et al., assigned to Eltron Research & Development, Inc. refers at Col. 1 lines 45 through 66 to Lyon which teaches the use of metal oxide catalysts in the partial oxidation of hydrocarbon feeds. The reference does not refer to using inert metallic dilluents in a reactor bed.
There are a number of United States patents assigned to Petro-Tex Chemical Corporation issued in the late 1960's that disclose the use of various ferrites in a steam cracker to produce olefins from paraffins. The patents include U.S. Pat. Nos. 3,420,911 and 3,420,912 in the names of Woskow et al. The patents teach introducing ferrites such as zinc, cadmium, and manganese ferrites (i.e. mixed oxides with iron oxide). The ferrites are not inert and release oxygen to react with the hydrocarbon stream. The ferrites are introduced into a dehydrogenation zone at a temperature from about 250° C. up to about 750° C. at pressures less than 100 psi (689.476 kPa) for a time less than 2 seconds, typically from 0.005 to 0.9 seconds. The reaction appears to take place in the presence of steam that may tend to shift the equilibrium in the “wrong” direction. Additionally the reaction does not take place in the presence of a catalyst.
U.S. Pat. No. 2,267,767, issued Dec. 30, 1941 to Thomas, assigned to Universal Oil teaches the use of non porous metallic substrates as supports for catalysts for the treatment of hydrocarbons. The metallic substrates are treated with non aqueous solutions of a metallic alkoxide and an alkyl ortho silicate. The substrate appears to be a component for the reaction. The metal oxides may be alumina, zirconia, thoria, vanadia, magnesia and other metal oxides which are active in the cracking and or reforming reactions.
U.S. Pat. No. 2,478,194 issued Aug. 9, 1949 assigned to Houdry Process Corporation teaches a composite shaped catalyst and support comprising a metallic component such as iron or steel. The metallic component may take a number of shapes such as an “I” a cross, or even the shape of a child's jack. The catalytic component is then applied to the metallic support to form the catalyst. The metallic component provides an oxidation promoter not an inert heat sink.
The fixed bed reactor is a workhorse of the petrochemical and refining industry. In commercial reactors the ratio of reactor diameter to effective particle diameter is at least 50:1 generally greater than 500:1. Catalyst supports generally have a low thermal conductivity. Under these conditions there is a low transfer of heat from the interior of the fixed bed to the reactor wall where heat may be dissipated. These conditions may lead to localized hot spots which can be the center for a runaway reaction, particularly for exothermic reactions.
The present invention seeks to provide a fixed bed of catalyst and a metallic diluent having a thermal conductivity of greater than 30 W/mK (watts/meter Kelvin) within the reaction temperature control limits to permit the transfer of heat within the bed and also out of the bed.